The liquid cooled brake unit or apparatus of the invention relates to the general type of brake apparatus or units disclosed in U.S. Pat. No. 4,415,067 and No. 4,821,947 which issued to the Assignee of the present invention and which are herein incorporated by reference. In such a brake unit, it is highly desirable to provide for recirculating cooling oil between the rotatable brake discs and the non-rotating brake plates, especially when the brake plates and discs are being clamped together for braking. The oil dissipates heat from the brake plates and discs and provides the brake unit with an extended operating life. It is also desirable to provide for automatically compensating for any wear of the brake plates and discs without requiring the brake unit to be opened and disassembled for adding shims. It has also been found desirable to construct the brake unit housing in two sections with each section providing for a sub-assembly in order to simplify manufacture of the brake unit and disassembly during servicing. While the braking operation is preferably performed by a set of compression springs, and the release of the brake is performed by a fluid actuated piston or an electrical coil, as shown in the above patents, it is also desirable to provide for manually releasing the brake unit to permit rotation of the shaft when the electrical power or air pressure is not being supplied. In addition, while the brake unit is normally operated with a horizontal axis, it is desirable to incorporate means which provide for effective recirculation of the cooling oil when the brake unit is operated with a vertical axis.